The invention relates to a method for imaging electrical barrier layers such as pn junctions in semiconductors by means of processing particle-beam-induced signals in a scanning corpuscular microscope.
Precise knowledge of the potential distribution or dopant distribution in the inside of the semiconductor crystal is of significance for the development of VLSI components. Depth-dependent dopant profiles can be calculated by means of computer simulation or, for example, can be measured by means of secondary ion mass spectrometry (SIMS). The depth of a pn-junction can be identified by means of electrical measurements.
Due to increasing miniaturization, however, lateral effects produced by scattering or diffusion of the dopant, for example under-diffusion at mask edges, are also of great significance. The measurement of these lateral effects with sufficiently high topical resolution (approximately 0.1 .mu.m) is a hitherto unresolved problem.
It is known to image pn-junctions with the assistance of the induced current in a scanning electron microscope (EBIC: electron beam induced current). The definition of a pn-junction, however, cannot be represented with the required precision given such a known method.